It is known from the U.S. Pat. No. 4,849,300 to make tools from hard compound materials containing 30-70 vol % of hard constituents in the form of carbides, nitfides and/or carbonitrides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and/or W in a matrix based on Fe, Ni and/or Co, said hard constituents forming a core which is co-extruded with a metallic cover such as tool steel. The cover is either removed before the final shaping or retained as a major supporting part of the tool.
In certain applications such as band saws or large circular saws the required volume fraction of hard constituents is so small and the technical demands on the supporting parts of the tool so specialized that it is not economically feasible to produce the whole tool by co-extrusion as described in the aforementioned patent.
It is known to make saw blades with tips made of hard material such as cemented carbide with cobalt matrix, either as comparatively large prismatic tips brazed to the tooth bodies according to patent U.S. Pat. No. 4,784,033, or as small spheres brazed or welded to the tooth bodies according to U.S. Pat. No. 3,104,562 or as small cylindrical parts welded to the tooth bodies according to patent publication DE G 71 27372.
The above hard compound materials are, especially when the titanium nitfide content is high, difficult or impossible to braze since they are not wetted by the brazing alloy, and not possible to weld because they are not stable at welding temperatures. The invention concerns a new saw tooth design which allows brazing of tips of hard compound materials using normal brazing alloys.